Re: 100% positive offset

If you take and attach the ground lead of your scope to the battery ground of the Beck unit and then monitor 1 output or the other or even both outputs on different channels, you will see that it actually does not go negative although the polarity does get reversed.

This is a biphasic positive output, not true alternating current although it does appear that way when you connect the scope ground to one output and the other output to the scope input.